氩等离子体后辉光区对聚四氟乙烯膜表面的优化改性

四氟

摘　要:在理想管式反应器中，采用Langmuir双电子探针和电子自旋共振（ESR）诊断技术分别定量测定了氩等离子体场中各活性物种的轴向分布，并利用氩等离子体放电区及后辉光区对聚四氟乙烯（PTFE）进行了表面改性．通过接触角测量、扫描电子显微镜和X射线光电子能谱分析比较了改性前后常规及后辉光氩等离子体对PTFE表面结构及性能的影响．结果表明，氩等离子体中电子及离子浓度随轴向距离的增大迅速降低，30cm后接近于0，而自由基浓度则降低缓慢，40cm处仍为初始浓度的96％．氩等离子体放电功率、处理时间和气体流量强烈影响着PTFE表面润湿性的改善效果．后辉光区因抑制电子和离子的刻蚀作用，强化自由基反应，使改性效果远优于常规氩等离子体．经氩等离子体后辉光区短时间（30s）处理后，PTFE表面化学成分发生了变化，F／C原子比从3．27降至2．30，O／C原子比从0．02增至0．09．脱氟作用和含氧基团（如C=O）的引入是有效改善PTFE表面润湿性的关键因素．
关键词:氩等离子体 后辉光 聚四氟乙烯 表面改性

Optimizing the Surface Modification of Poly （tetrafluoroethylene） in a Flowing Afterglow Ar PlasmaLIU Hong-Xia, CHEN Jle-Rong1. Department of Environmental Engineering, 2. State Key Laboratory of Multiphase Flow in Power Engineering, Xi＇an Jiaotong University, Xi＇an 710049, ChinaAbstract:In the ideal tube-reactor, double Langmuir electron probe and electron spin resonance （ESR） were used to measure the distribution of electrons, ions and free radicals in Ar plasma. Surface modification of poly （tetrafluoroethylene） （PTFE） in Ar plasma active discharge zone and afterglow zone were studied respec- tively. The surface properties were characterized via the contact angle measurement, scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）. The results show that the concentration of electrons and ions decreases rapidly with increasing the distance from the center of induction coil, which approximated to 0 at 30 cm, whereas the concentration of free radicals reduces slowly, which is 96% of initial one. The surface wettability of PTFE strongly depends on the plasma radio frequcency （RF） power, the treatment time and the argon flux. But regardless of conditions, Ar afterglow plasma is more effective than the conventional Ar plasma in PTFE surface modification because the enhanced reaction of radicals and the inhibited etching action of discharged particles. After a short treatment time（30 s） by Ar afterglow plasma, the surface composition of PTFE is modified and the F/C atomic ratio decreases from 3.27 to 2. 30, O/C atomic ratio increases from 0. 02 to 0. 09. Both the defluorination from PTFE and introducing oxygen functionalities （e. g. C = O） into PTFE surface are the primary reasons of surface wettability improvement.
Key words:Argon plasma; Afterglow; Poly（tetrafluoroethylene） ; Surface modification